With your hair dry, lift up a very small section of hair. Don't pull it, just lift it right up or lift to the side, depending on the length of your hair. Hold the hair between your first and second fingers. (not the thumb) If the section you have lifted up is uneven, just cut a very small straight line a little below the tops of your fingers. Don't tug or stretch because you will cut off too much. Be certain to cut beneath your fingers very carefully. Take your time, and you will really see a big difference in your hair.
To stop split ends in the first place, after you wash and condition your hair, comb it gently with a wide tooth comb. Wet hair is very fragile.
Also, be sure to do a deep conditioner once a week, with your wet hair wrapped in plastic wrap under a shower cap. Leave the deep conditioner on for 1 hour. For even deeper conditioning, you can use a cap style hair dryer.